Hi I want some clarification about discussion api do we need any plan to use discussion api

HI Team,
I want some clarification about discussion api do we need any plan to use discussion api. & One more regarding Oauth2 i am using app for creating connection if we generate one access token after that if we generate another access token will other old token be expire? I am facing this issue my old token is getting expire .

Please help us .

Thanks in advance…!